The accidental spillage of hydrocarbons with the resulting environmental damage unfortunately is a fairly common occurrence. However, as yet there has been no completely satisfactory method of retaining and retrieving spilled hydrocarbons. The most visible use of such methods has been in the "clean up" operations following large volume crude oil spills from sea-going oil tankers. Efforts to deal with such spills have included containment using floating booms and subsequent attempts to separate the contained oil from sea water using various methods. However, such booms are generally only effective in relatively calm weather and known separation processes are relatively slow and unsuitable for dealing with large volume oil spills.
It has long been known that surfactants, dispersants and wetting agents have the ability to emulsify hydrocarbons in varying degrees. This fact has been put to use historically to aid in the removal of hydrocarbons from, for example, beaches and also for example, to assist in the dispersal of hydrocarbons spilled upon open waters.
The teachings of the U.S. Pat. Nos. 3,577,340 to Paviak, May 4, 1971; 3,639,255 to Boardman, Feb. 1, 1972; and 4,197,197 to Abaeva, Apr. 8, 1980, disclose various novel surfactants that have utility in dissisipating oil films or spills in open water. As a method for remediation of oil spills, the use of surfactants, as described in the documents listed above, may only dilute the oil and does not eliminate or remove it. There is, in fact, considerable evidence that the chemically dispersed or emulsified hydrocarbons are more toxic to crustaceans and fish than the original undispersed hydrocarbon.
When spilled crude oil is washed ashore, the removal of the oil becomes even more difficult. In some circumstances the soiled beach material is simply removed. Where this is impractical, for example, on rocky beaches, the conventional method of cleaning involves the use of high pressure steam or water to wash the oil from the shore, although this method is slow and labour intensive, and still relatively ineffective.
The use of silica or silicate for remediation of hydrocarbon spills is also known, for example, Whittington et al., in U.S. Pat. No. 3,843,306, of Oct. 22, 1974, discloses the use of a surface treated, urethane foam-like, silicate foam that absorbs, amongst other things, hydrocarbons.
Kozar, in U.S. Pat. No. 4,256,578 of Mar. 17, 1981, discloses the use of metasilicates to reclaim used oil by adjusting the pH of an oil/water mixture and heating, thereby solubilizing the oil contaminants in the aqueous phase and thus allowing the oil to be re-used.
Black et al., in U.S. Pat. No. 4,518,506, of May 21, 1985, describes the use of a surface treated, expanded silicate aggregate for the absorption of floating oils from water.
All of the above uses of silicates or silicas rely simply on physical absorption or pH adjustment.